Biodiversity as insurance



Diversity buffers against functional changes
No one species fills all the roles of an ecosystem

Today’s topic: Species Diversity



  • Intricate webs of interacting organisms
    • 2,000,000 species are known
    • ~18,000 new species discovered per year
    • estimated 87% of Eukaryotas unknown


  • Reflects billions of ways organisms have adapted, over and over, to a changing planet


  • Humans relentlessly alter ecosystems
    • aquatic and terrestrial
    • ~150 species go extinct each day

Measuring biodiversity (e.g. Simpson’s or Shannons index)


Species types (native, endemic, non-native, exotic, invasive)


The march of the cane toad


Exotic vs Invasive


Species diversity declines from tropics


Species diversity declines at altitude


Mapping biodiversity: Soils


Mapping biodiversity: Oceans


Ecoregions: Where biodiversity hotspots exists


Hotspots: Andean uplift and bird diversity


Hotspots: Endemic species of Madagascar


Threats to biodiversity


Threats: Invasive species are increasing






  • Change physical and biotic environment



  • Aquatic ecosystems heavily affected



  • Impacts outweigh natural extinction rates

Ecoregions versus humans


Homogenization: ecosystems losing their uniqueness




  • Replacement of native species by exotics
    • invasives are highly competitive


  • Taxonomic homogenization
    • increased similarity of species
    • plants, insect, fish, birds & mammals


  • Biotic homogenization tied to humans
    • landscape simplification
    • habitat loss

Homogenization: Megafauna


Are we experiencing a new mass extinction?


Extinction versus humans